A theologian, born about 1720 at Castelsarrasin (Diocese of Montauban), died in 1782 at Glogau, famous through an irreligious thesis. Having finished his preliminary studies, he went to Paris, where he lived in many seminaries, especially in that of St-Sulpice. He very soon became acquainted with the principal publishers of the "Encyclopédie", and supplied them with the article on "Certitude". About the end of 1751, he presented himself for the doctorate, driven, as a mémoire of that time says, "by the incredulous, who, in order to justify his blasphemies, wanted to have his doctrine approved by the Faculty". Prades wrote a very long thesis, which the examiners accepted without reading. The defence, which took place on 18 November, was very sharp, and the scandal broke out. On 15 December following, the Faculty declared several propositions to be "worthy of blame and censures". On 15 January following, the censure was published. According to Abbé de Prades, the soul is an unknown substance; sensations are the source of our ideas; the origin of civil law is might, from which are derived all notions of just and of unjust, of good and evil; natural law is empiric; revealed religion is only natural religion in its evolution; the chronology of Moses's books is false; the healings operated by Jesus Christ are doubtful miracles, since those operated by Esculapius present the same characteristics. The archbishop of Paris and several bishops approved the censure; afterwards, on the 2 March, Benedict XIV condemned the thesis; at last the Parliament of Paris issued a decree against the author; further, Stanislas, Duke of Lorraine, incited the Faculty against the Abbé.

The latter found a refuge in Holland, where he published his "Apology" (1752). It consists of two parts: a third part containing "reflexions upon the Pastoral Letter of the bishop of Montauban and the Pastoral Instruction of the bishop of Auxerre" as written by Diderot. Le Père Brotier published "the Survey of the Apology of the Abbé de Prades" (1753). The question is whether the Abbé de Prades is not the author of an "Apology of the Abbé de Prades" in verse. Upon the recommendation of Voltaire and of the Marquis of Argens, the Abbé became lector to Frederick of Prussia and went to Berlin. Frederick gave him a pension and two canonries, the one at Oppeln, the other at Glogau. From the year 1753, negotiations were entered upon between the Abbé de Prades and the Bishop of Breslau, Philip von Schaffgotsch, with a view to a recantation. Frederick himself induced the Abbé to return to "the bosom of the Church". Benedict XIV and the Cardinal of Vencin wrote the formula of recantation which was signed by the Abbé. In 1754, the Faculty of Paris again inscribed the Abbé upon the list of bachelors. The Abbé de Prades became the archdeacon of the Chapter of Glogau, and died in that town in 1782.

Besides the works quoted, he left an "Abrégé de l'histoire ecclésiastique de Fleury", tr. Berne (Berlin, 1767), II vols., with a violently anti-catholic preface written by Frederick II. This would make us doubt the sincerity of the recantation of the Abbé de Prades. To him is generally ascribed "le Tombeau de la Sorbonne" translated from Latin (1782). According to Quérard, he left in manuscript a complete translation of Tacitus, which remains unpublished. What has become of the manuscript is unknown. It is said also that he worked, before leaving France, at a Treatise on "the Truth of Religion".